fix(deps)!: remove @backstage/backend-common

[dotboris]

Description

This PR remove @backstage/backend-commons as a dependency.

With this change, users of the legacy system are now required to pass in a config and auth to createRouter and they are required to pass options to createPagerDutyServiceAction (the config field was already required).

This is technically a breaking change and I'm honestly not quite sure how to handle it because it depends on how the PagerDuty team wants to handle support for the legacy backend system. I opted to open this PR early to get an idea of what the code change would look like and what kind of an effect it would have.

Issue number: (e.g. #129)

Affected plugin

• backstage-plugin
• backstage-plugin-backend
• backstage-plugin-scaffolder-actions
• backstage-plugin-entity-processor

Type of change

• New feature (non-breaking change which adds functionality)
• Fix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• I have performed a self-review of this change
• Changes have been tested
• Changes have been tested in dark theme
• Changes are documented
• Changes generate no new warnings
• PR title follows conventional commit semantics

If this is a breaking change 👇

• I have documented the migration process
• I have implemented necessary warnings (if it can live side by side)

Acknowledgement

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